Abstract

Precocene II (6,7-dimethoxy-2,2-dimethyl-2-chromene) was the main constituent isolated from Ageratum
conyzoides L. and reportedly possessed antifungal activity. The study investigated the isolation,
purification and toxicological effects of precocene II from A. conyzoides in Sprague Dawley rats.
Precocene II was isolated from the petroleum ether fraction of the plant and the structure was
determined by 1H-,13C-,DEPT-NMR and MS spectral techniques. Three groups of eight rats per group
were used for the study. While groups B and C were respectively administered with 25 and 50 mg/kg of
precocene II in 0.25% CMC-Na for 11 days by gastric intubation, group A was administered with 0.25%
CMC-Na and served as the control group. After the last treatment, animals were fasted overnight and on
the 12th day, they were injected intravenously with 0.2 ml/kg body weight of phenobarbital. Animals
were subsequently dissected from the abdominal region; blood was collected from the pulmonary vein
into EDTA anti-coagulated and non anti-coagulated tubes. The liver, kidney and spleen tissues were
extracted into separate bottles for histopathological examinations. Results from hematological study
indicated that the white blood cell (WBC), red blood cell (RBC), plateletcrit (PCT) and mean corpuscular hemoglobin count (MCHC) were significantly higher across the treated groups. Biochemical result showed that serum glucose level was significantly reduced in the treated groups. No apparent damage was noticed in the liver, kidney and spleen tissues. The result therefore suggests that precocene II
possesses hypoglycemic property and could alter some hematopoietic elements but was not toxic to the liver, kidney and spleen tissues.